Intense polar temperature inversion in the middle atmosphere on Mars

Current understanding of weather, climate and global atmospheric circulation on Mars is incomplete, in particular at altitudes above about 30 km. General circulation models for Mars [1,2,3,4,5,6] are similar to those developed for weather and climate forecasting on Earth and require more martian observations to allow testing and model improvements. However, the available measurements of martian atmospheric temperatures, winds, water vapour and airborne dust are generally restricted to the region close to the surface and lack the vertical resolution and global coverage that is necessary to shed light on the dynamics of Mars' middle atmosphere at altitudes between 30 and 80 km (ref. 7). Here we report high-resolution observations from the Mars Climate Sounder instrument [8] on the Mars Reconnaissance Orbiter [9]. These observations show an intense warming of the middle atmosphere over the south polar region in winter that is at least 10–20 K warmer than predicted by current model simulations. To explain this finding, we suggest that the atmospheric downwelling circulation over the pole, which is part of the equator-to-pole Hadley circulation, may be as much as 50% more vigorous than expected, with consequences for the cycles of water, dust and CO2 that regulate the present-day climate on Mars.

[1]  Clive D Rodgers,et al.  Inverse Methods for Atmospheric Sounding: Theory and Practice , 2000 .

[2]  Stephen R. Lewis,et al.  Influence of water ice clouds on Martian tropical atmospheric temperatures , 2008 .

[3]  Jeffrey R. Barnes,et al.  Mars atmospheric dynamics as simulated by the NASA Ames General Circulation Model: 1. The zonal‐mean circulation , 1993 .

[4]  B. Jakosky,et al.  Mars: North-polar atmospheric warming during dust storms , 1987 .

[5]  P. Gierasch,et al.  The vertical structure of limb hazes in the Martian atmosphere , 1986 .

[6]  Mark T. Lemmon,et al.  Constraints on dust aerosols from the Mars Exploration Rovers using MGS overflights and Mini‐TES , 2006 .

[7]  Moustafa I. Chahine.  A general relaxation method for inverse solution of the full radiative transfer equation. , 1972 .

[8]  P. Hartogh,et al.  Winter polar warmings and the meridional transport on Mars simulated with a general circulation model , 2007 .

[9]  Robert M. Haberle,et al.  Some effects of global dust storms on the atmospheric circulation of Mars , 1980 .

[10]  T. E. Burke,et al.  Atmospheric and surface properties of Mars obtained by infrared spectroscopy on Mariner 9. , 1973 .

[11]  J. Forbes,et al.  Global and seasonal distribution of gravity wave activity in Mars' lower atmosphere derived from MGS radio occultation data , 2006 .

[12]  S. Warren,et al.  Optical constants of ice from the ultraviolet to the microwave. , 1984, Applied optics.

[13]  A. Seiff,et al.  Structure of the atmosphere of Mars in summer at mid-latitudes , 1977 .

[14]  S. Smrekar,et al.  An overview of the Mars Reconnaissance Orbiter (MRO) science mission , 2007 .

[15]  Gang Li,et al.  The HITRAN 2008 molecular spectroscopic database , 2005 .

[16]  David A. Paige,et al.  Mars Climate Sounder: An investigation of thermal and water vapor structure, dust and condensate distributions in the atmosphere, and energy balance of the polar regions , 2007 .

[17]  R. Haberle,et al.  Zonally Symmetric Response to Atmospheric Tidal Forcing in the Dusty Martian Atmosphere , 1988 .

[18]  Kevin Hamilton,et al.  Comprehensive Model Simulation of Thermal Tides in the Martian Atmosphere , 1996 .

[19]  Mark I. Richardson,et al.  PlanetWRF: A general purpose, local to global numerical model for planetary atmospheric and climate dynamics , 2007 .

[20]  D. Diner,et al.  Remote sensing of the atmosphere of Mars using infrared pressure modulation and filter radiometry. , 1986, Applied optics.

[21]  Stephen R. Lewis,et al.  Improved general circulation models of the Martian atmosphere from the surface to above 80 km , 1999 .

[22]  E. Schneider.  Martian great dust storms: Interpretive axially symmetric models , 1983 .

[23]  John C. Pearl,et al.  Thermal Emission Spectrometer results: Mars atmospheric thermal structure and aerosol distribution , 2001 .

[24]  Stephen R. Lewis,et al.  A climate database for Mars , 1999 .

[25]  C. Leovy,et al.  Mariner 9 Television Limb Observations of Dust and Ice Hazes on Mars , 1978 .

[26]  R. John Wilson,et al.  A general circulation model simulation of the Martian polar warming , 1997 .

[27]  David P. Hinson,et al.  Temperature inversions, thermal tides, and water ice clouds in the Martian tropics , 2003 .

[28]  Jeffrey R. Barnes,et al.  Possible effects of breaking gravity waves on the circulation of the middle atmosphere of Mars , 1990 .